Home & Studio Recording - Jan 1985 Ibanez HD1000 Harmonics Delay

Ibanez HD1000 Harmonics Dela...

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Ibanez HD1000 Harmonics Delay

Good harmonisers are expensive and so most home recordists will probably consider them to be a luxury, or even a gimmick, especially when there are more down to earth items still to be bought. What Ibanez have done is to create a time processor capable of functioning as both a harmoniser and a digital delay, and for the home user on a budget this makes much more sense.

For those as yet unaware as to what a harmoniser can do, a brief look at its operating principles is in order.

Principle

Generally speaking, a harmoniser is capable of shifting the pitch of any sound source either up or down, usually around an octave either way. Any programme material may be processed, either monophonic or polyphonic, and the output pitch is always harmonically related to the original.

So how is this achieved?

Well today's devices are all digital of course. The input signal is digitised, loaded into memory (RAM), and then clocked out a short time later, just as in a delay unit. To achieve a pitch change, the sound must be clocked out of RAM at a different rate to that at which it is clocked in, and it is this unalterable fact that creates the real headaches for the designers.

It is obvious that if you are pitch-shifting upwards and consequently taking information out of RAM faster than you put it in, you are very soon going to run out of data. Bank accounts sadly work in a similar way! To get around this fundamental problem, some bits of information are used twice, just to fill up the gaps and conversely, if the pitch is to be shifted downwards, some information is discarded as there is not time to output it all.

So, we have ascertained that the output from a harmoniser consists of a great number of short sections of sound joined together, and it is the quality of these joins or splices that determines just how good the result sounds. If the sections are just joined end to end, there will undoubtedly be audible glitches or clicks but at the other end of the scale, an intelligent system that joins sections when both waveforms are crossing a zero point or whatever costs quite a lot of money.

Whatever you do, some side effects will be audible, so Ibanez have opted for a parallel delay line system where each channel of delay handles alternate sections of sound. At the crucial splice point, one sound is faded out whilst the other is faded in, thus eliminating any clicks but the overall result is still 'lumpy'.

HD1000

The HD1000 is built in the mandatory 1U high rack case and is equipped with the usual array of knobs, buttons and LEDs. Unusual, however, is the liquid crystal display which functions as an input level meter, a delay time indicator and a pitch shift readout, as well as telling you what mode of operation you are currently employing.

In delay mode, there are three selectable ranges, 0-126ms, 0-252ms, and 0-504ms, the system bandwidth being 8kHz, 4kHz and 2kHz respectively. Delay time is increased or decreased by means of the now familiar up/down buttons whereas the pitch shift in harmoniser mode is directly controlled by means of coarse and fine rotary controls giving a maximum shift of ±13 semitones.

An LFO is built in for modulation effects and this has conventional depth and speed controls giving a sweep range of 0.03Hz to 10Hz, this being most useful in the delay mode where chorus and flanging can be produced.

The number of delay repeats is again conventionally adjusted by means of a feedback control and in the harmoniser mode, this causes each repeat to be further shifted in pitch.

Lastly on the front panel, two level controls, one for effect and one for dry, take the place of the more usual level and mix controls. The power switch needs little explanation.

The back of the case reveals a row of quarter inch jack sockets for input, output and footswitch. Additionally, an effects loop is provided so that a further signal processor may be patched into the feedback loop and this opens up interesting possibilities, particularly in the harmoniser mode of operation.

Delay Effects

As you may have inferred from the delay/bandwidth figures, only the shortest range of 0-126ms gives anything like a decent frequency response though the other two ranges may be useful for special effects.

This limits the use of this section to ADT-type delays, flanging or chorus, but if you already have another DDL tied up producing echoes, these facilities are very welcome. Used in this way, the sounds are adequately bright and pleasantly free from unwanted background noise though a wider LFO sweep range would have improved the flanging.

Harmonising

This is what the machine's ail about and it does it well for the price. The more pitch shift you introduce, the 'lumpier' the sound, but providing this is mixed in with the original, the effect is quite convincing.

Using a shift of only ten cents or so, a good chorus or doubling effect can be created and the inevitable slight delay caused by the circuitry actually helps to make ADT effects more natural.

The colouration of the effect is interestingly modified by the application of feedback as successive repeats are further shifted in pitch each time they are recycled. A delay line inserted in the feedback loop helps to emphasise this but remember, if you are just using large amounts of pitch shift, you will only get two or three repeats before the signal disappears up its own anti-aliasing filters.

Conclusions

The unit was tested on voice, keyboards, guitar and even drums and all the results were musically viable if the mix of direct and pitch-shifted sounds remained sensible.

This is not a perfect harmoniser by any means but for the price of a standard digital delay, it does offer scope for experimentation. The fact that it will also chorus and flange makes this a versatile multi-effects unit, but the longer delay times sound exceedingly dull and 'woolly' due to the heavily restricted bandwidth.

With this unit, you can be as subtle or as outrageous as you like, so if you need a second DDL for short delay effects, this one will do everything you need and harmonise into the bargain.

The Ibanez HD1000 has a recommended selling price of £404 including VAT. Details from Summerfields, (Contact Details).